Put it this way PL clubs are not a fan of the tradition of drinking in the pub and walking up 15 minutes before kick off and then leaving without putting any extra money in their over inflated catering or club shops.
They want you to spend in the club shop, feed and water yourself onsite. Tourist fans are more likely to spend in the club shop for souvenirs and eat at the ground out of convenience.
I like the way lots of clubs with an airport in their city put a club shop in the departures, Liverpool you cannot not go past it or see on your way to departures.